Interesting execution for an interesting subject. I find that your writing flows very well from one paragraph to the next, keeping the reader engaged from start to finish.
Like the reviewer below, I think the line “I could already see her face light up with delight once she saw my gift” is just a tad bit confusing to read. I’d recommend changing it to something like “I could already see her face lighting up with delight at the sight of my gift”
I’d also recommend changing “I could almost pet it” to “I could almost grasp it” since the character is trying to catch the butterfly. “Pet” seems to imply something more stationary – and more affectionate. Besides this, the phrase “something came into my path” kind of suggests that the twig was moving towards the character, so I think changing it to “something tripped me, sending me tumbling to the ground” might be more appropriate.
Lastly, I just want to say I really adore the third-last paragraph; it’s both horrifying and poignant in its details. I like the use of “plucking” as if the butterfly were an object or plant. I also like how you write that it “floated” to the ground. It slows down the movement in the scene and really gives both the reader and the characters time to appreciate what just happened.
Keep up the great work!